Solar panels for a 3-bed house: cost, size and savings in 2026

The short answer

Most three-bedroom homes suit a solar system of about 3kWp to 4.5kWp, which is roughly 8 to 12 panels. Based on the Energy Saving Trust’s typical price of £7,600 for 4.5kWp, that works out at about £5,000 to £7,600 before any battery. How much you save depends mostly on how much of the electricity you use yourself and what you are paid for the rest.

How much electricity does a 3-bed house use?

There is no official figure for a three-bedroom home, because use depends far more on who lives there and what they run than on the number of bedrooms. The closest guide is Ofgem’s set of typical figures, updated from July 2026, for homes on a single-rate electricity meter:

• Low use: 1,600kWh a year
• Medium use: 2,500kWh a year (the figure used for the headline price cap)
• High use: 3,800kWh a year

Homes on Economy 7 or another two-rate meter use more, with a medium figure of 3,400kWh. A busy family home in a three-bed house will often sit somewhere between medium and high. Your own figure is on your annual statement, and it is worth finding before you ask for quotes.

What size system fits a 3-bed house?

Government figures for solar homes give a median load factor of 9.6% in 2023/24 and 9.2% in 2024/25, a year when sunshine hours were the lowest since 2012/13. We turned those into yearly output: each kWp of panels made about 840kWh in 2023/24 and about 806kWh in 2024/25 (load factor multiplied by the 8,760 hours in a year).

Dividing your yearly use by about 840 gives a system that would make roughly as much electricity as you use over a year:

• 2,500kWh a year: about 3kWp
• 3,800kWh a year: about 4.5kWp

The Energy Saving Trust says the average home system is 4.5kWp, typically around 12 panels covering 20 to 30 square metres of roof. Chimneys, roof windows and shading all reduce the usable space, so the installer’s survey decides what actually fits. Our guide to how many solar panels you need explains sizing in more detail.

What it costs

The Energy Saving Trust puts a typical 4.5kWp system at about £7,600. We scaled that in a straight line to other sizes, and scaled the panel count from the same figure of 12 panels for 4.5kWp, so treat these as rough guides rather than quotes. Installation of solar panels and batteries has 0% VAT until 31 March 2027, after which it goes back to 5%.

A battery adds to this. The Energy Saving Trust says a 5kWh battery system costs around £4,600. For a fuller breakdown, see our guide to solar panel costs by system size.

Worked example: two 3-bed homes

Here are two households in similar three-bed houses. We assumed someone is at home all day and used these figures:

• Output: 840kWh a year for each kWp, as above.
• Share used at home: the MCS self-consumption tables for a home occupied all day. Homes that are empty during the day use less, so would save less.
• Electricity price: 26.32p per kWh, the Ofgem price cap rate for Direct Debit customers from 1 October to 31 December 2026.
• Export payments: 4p to 6p per kWh, the range of Smart Export Guarantee tariffs open to anyone that Which? found in April 2026.

For example, Home B uses 30% of its 3,780kWh, which is 1,134kWh. At 26.32p that saves about £298. The other 2,646kWh is exported, earning about £106 at 4p or £159 at 6p. We have ignored energy lost in charging and discharging the battery and any change in prices, so these are estimates.

Why the export rate matters so much

These paybacks are longer than the 9 to 12 years the Energy Saving Trust gives for typical homes in its own examples, which use its own assumptions about export payments. Ours use only the plain export rates open to anyone, so they are on the cautious side.

The rate you are paid for exported electricity makes a big difference. Which? found rates open to anyone ranged from 1p to 6p per kWh in April 2026, while the best deals paid 20p to 25p but came with conditions, such as having your solar panels and battery installed through that supplier. If Home B with a battery earned 20p for its 1,323kWh of exports, its yearly total would rise to about £910 and its payback would fall to about 13 years. Our guide to the Smart Export Guarantee explains how to choose a tariff.

Two other things work in your favour. The Energy Saving Trust says panels should last 25 years or more, although the inverter usually needs replacing after around 12 years. And the more of your electricity you use in the daytime, for example running the washing machine while the sun is out, the more you save.

Is a battery worth it for a 3-bed house?

In our example the battery more than doubles the share of solar electricity Home B uses, but it also adds about £4,600 to the cost, so the payback barely changes. The Energy Saving Trust says battery savings can be significant but won’t always be enough on their own to justify the cost. A battery tends to make more sense if you use a lot of electricity in the evening, or if you want a tariff that pays a higher export rate or lets you charge from the grid at cheap times. You can compare solar battery quotes alongside quotes for panels alone.

What to do next

Find your yearly electricity use, then try your own numbers in our solar savings calculator. When you are ready, get free solar quotes from an installer who covers your area. Getting quotes before 31 March 2027 means you pay 0% VAT rather than 5%. It’s free and there’s no obligation.